1. Field of the Invention
The present invention relates to the production of antistatic carpets and compositions effective for this purpose, including active agents capable of migrating into carpet fibers. The invention also concerns the acceleration of the rate at which antistatic properties are imparted to the carpet fibers.
2. Description of the Prior Art
The uncomfortable, and sometimes painful and/or dangerous discharge of static electricity from a person's body to a grounded object which occurs after the person has walked on common carpet materials is an all too familiar and unpleasant phenomenon. Carpets manufactured from both natural fibers, such as, wool, and synthetic fibers, such as, fibers of acrylics, nylons, polyesters and lower polyolefins, such as, polyethylene and polypropylene, all exhibit this undesirable characteristic, especially under low humidity conditions.
Many attempts have been made to overcome or at least mitigate the problem. Investigation has shown that the level of human sensitivity to static discharge occurs at about 3,000 volts and above. Accordingly, a guideline in the search for solutions to the problem has been the reduction of static build-up to below the human sensitivity threshold of 3,000 volts.
We are aware that according to a process developed by Herculite Protective Fabrics Corporation, assignee of this invention, it has been discovered that a variety of active properties can be imparted to solid, non-porous polymeric substrate materials by a technique which comprises applying to the substrate a solid, non-porous layer of a polymeric composition containing active agents capable of migrating from the layer into and throughout the substrate. The migrating agent is incorporated in the layer in an amount sufficient to produce an effective level of activity on the surface of the substrate which is not in direct contact with the layer. The application of the Herculite technology, known generally in the industry as the HERCON process to the production of antistatic and electrically conductive polymeric materials is broadly described in U.S. Pat. No. 3,705,938 issued Dec. 12, 1972 and in pending application Ser. No. 255,144 which is a divisional application related to the just mentioned issued patent.
We are also aware that U.S. Pat. No. 3,510,386 Goins et al. discloses an antistatic carpet structure in which antistatic agents are added to a layer applied to the primary carpet backing. According to the disclosure of this patent an antistatic composition consisting essentially of a mixture of an organic textile antistatic agent and a humectant is applied to a porous carpet backing so that the antistatic coating composition penetrates the backing of the carpet and wets the base of the pile fabric, but does not penetrate to the outer tips of the pile. Charges of static electricity built up in the pile are said to be dispersed throughout the entire carpet area by the antistatic layer and subsequently bled off into the ground or atmosphere.
Some other attempts to overcome the static problem in carpets have included the weaving of conductive filaments into the carpet, spraying conductive agents on to the carpet fibers and loading the carpet backing material with antistatic agents, such as, carbon black or other conductive fillers. All such attempts have suffered from one or more basic defects, including damage to the carpet structure or appearance, lack of durability of the antistatic effect, or greatly increased cost.
Accordingly, it is an objective of the present invention to provide a new approach to rendering carpets antistatic in accordance with which durable antistatic properties are imparted to the carpet fibers themselves.
It is a further object of the present invention to provide a method for rendering carpets antistatic so that the antistatic effect is accomplished, economically, rapidly and without damage to the appearance or structure of the carpet.
Another object of the invention is to provide carpets with durable antistatic properties.